Copper Catalyst Research Articles

Electroreduction of CO to 2.8 A cm⁻2 C2+ Products: Maximizing Efficiency with Minimalist Electrode Design Featuring a Mesopore-Rich Hydrophobic Copper Catalyst Layer.

This work shows how hydrophobicity and porosity can be incorporated into copper catalyst layers (CLs) for the efficient electroreduction of CO (CORR) in a flow cell. Oxide-derived (OD) Cu catalysts are synthesized using K+ and Cs+ as templates, termed respectively as OD-Cu-K and OD-Cu-Cs. CLs, assembled from OD-Cu-K and OD-Cu-Cs, exhibit enhanced CORR performance compared to "unmodified" OD-Cu CL. OD-Cu-Cs can notably reduce CO to C2+ products with Faradaic efficiencies (FE) as high as 96% (or 4% FE H2). During CO electrolysis at -3000mA cm-2 (-0.73V vs reversible hydrogen electrode), C2+ products and the alcohols are formed with respective current densities of -2804 and -1205mA cm- 2. The mesopores in the OD-Cu-Cs CL act as barriers against electrolyte flooding. Contact angle measurements confirm the CL's hydrophobicity ranking: OD-Cu-Cs > OD-Cu-K > OD-Cu. The enhanced hydrophobicity of a catalyst is proposed to allow more triple-phase (CO-electrolyte-catalyst) interfaces to be available for CORR. This study shows how the pore size-hydrophobicity relationship can be harvested to guide the design of a less-is-more Cu electrode, which can attain high CORR current density and selectivity, without the additional use of hydrophobic polytetrafluoroethylene particles or dopants, such as Ag.

Comparative study of two mesoporous magnetic and MCM-41 supported Cu complex: High-performance heterogeneous catalysts for aqueous synthesis of tetrazole

The effects of the carrier were studied in the synthesis of tetrazole. Copper catalysts supported on CoFe2O4 and MCM-41 with serine ligands were prepared. Two mesoporous catalysts, CoFe2O4/Ser/Cu and MCM-41/Ser/Cu, (denote Serine with (Ser)) were synthesized and compared the activity of these catalysts in converting nitrile to tetrazole. The prepared material was characterized using powder X-ray diffraction (XRD),field emission scanning electron microscopy (SEM), energy-dispersive X-ray spectrometer (EDS), elemental mapping, vibrating-sample magnetometer (VSM), and nitrogen adsorption–desorption isotherm. The relation between the textural properties of the catalysts and the catalytic performance was investigated. The X-ray diffraction patterns showed the spinel ferrite type for CoFe2O4/Ser/Cu and amorphous SiO2 for MCM-41/Ser/Cu. The distinctive diffraction peaks in the diffraction curves of CoFe2O4/Ser/Cu, and MCM-41/Ser/Cu were identical to those of CoFe2O4, and MCM-41, confirming the preservation of these phases of supports throughout the functionalization processes and formation of -Ser/Cu moiety on the crystalline CoFe2O4 structure and non-crystalline silica structure. FE-SEM images showed the particles in CoFe2O4/Ser/Cu had an average diameter of 20–50 nm and in MCM-41/Ser/Cu had an average diameter of 50–250 nm. The images showed the uniformity and well-ordering of the particles. The slight aggregation in CoFe2O4/Ser/Cu particles implied that their clustering may be the result of modest attraction forces between them. MCM-41/Ser/Cu sample exhibited a type IV isotherm with an H1-type hysteresis loop and diagrams of the CoFe2O4/Ser/Cu showed a type IV isotherm (type H2 hysteresis loop). The MCM-41/Ser/Cu and CoFe2O4/Ser/Cu showed a mesoporous structure and capillary condensation occurred in the nearly cylindrical and ink bottle channels with non-uniform size or shape. The CoFe2O4/Ser/Cu showed surface area by BET and t-plot of 71.17 m2/g and 64.92 m2/g respectively, mean pore size of 14.06 nm, and pore volume of 0.250 cm3/g. The MCM-41/Ser/Cu showed surface area by BET and t-plot of 639.2 m2/g and 484.6 m2/g respectively, with a mean pore size of 5.44 nm, and pore volume of 0.869 cm3/g. The BJH pore size distribution was between 1 and 10 nm for the MCM-41/Ser/Cu and 1–20 nm for the CoFe2O4/Ser/Cu. Two catalysts were used for the synthesis of tetrazole. The CoFe2O4/Ser/Cu shows better activity in the synthesis of 5–substituted 1H-tetrazoles than the MCM-41/Ser/Cu sample despite its lowest surface area (71.17 m2/g). There is no reduction in the conversion of nitrile to tetrazole after the 6 cycles for CoFe2O4/Ser/Cu and after the 4 cycles for MCM-41/Ser/Cu.

Impact of the copper load on the performance of Cu/UiO-67 in CO2 hydrogenation to ethanol at atmospheric pressure

CO2 hydrogenation to ethanol could be a potential approach to reduce dependence on fossil resources, but faces challenges related to product selectivity and catalyst stability. MOFs, particularly UiO-67, acting as a support for copper catalysts can contribute to overcoming these limitations by stabilizing intermediates, creating interfaces that protect active sites against deactivation and potentially generating synergistic effects that favor the formation of the C-C bond. In this scenario, the present work aims to synthesize Cu/UiO-67 for application in the CO2 hydrogenation to ethanol at atmospheric pressure. The impact of the copper loading (5–60 wt%) on the catalyst physical properties and ethanol productivity was evaluated. Using XRD, N2 physisorption, TEM-EDS, FTIR and H2-TPR, it was possible to confirm the maintenance of the UiO-67 structure, which begins to deform with increasing copper content. Catalytic results showed that ethanol, methanol, propanol, carbon monoxide, and acetaldehyde have been produced. The selectivity of alcohols is related to the amount of copper, decreasing at high contents, indicating the importance of active sites interaction with SBUs units in alcohols formations.

Controlled Defective Engineering on CuIr Catalyst Promotes Nitrate Selective Reduction to Ammonia.

Electrochemical nitrate reduction reaction (NO3-RR) is a promising low-carbon and environmentally friendly approach for the production of ammonia (NH3). Herein, we develop a high-temperature quenched copper (Cu) catalyst with the aim of inducing nonequilibrium phase transformation, revealing the multiple defects (distortion, dislocations, vacancies, etc.) presented in Cu, which lead to low overpotential for NO3-RR and high efficiency for NH3 production. Further loading a low content of iridium (Ir) species on the Cu surface improves the reactivity and ammonia selectivity. The resultant CuIr electrode exhibits a Faradaic efficiency of 93% and a record yield of 6.01 mmol h-1 cm-2 at -0.22 VRHE exceeding those of state-of-the-art NO3-RR catalysts. Detailed investigations have demonstrated that the synergistic effect between multiple defects and Ir decoration effectively regulate the d-band center of copper, change the adsorption state of the catalyst surface, and promote the adsorption and reduction of intermediates and reactants. The strong H* adsorption ability of the Ir element provides more active hydrogen for the generation of ammonia, promoting the reduction of nitrate to NH3.

Insights into the Phases Transformation of Copper and Nickel Catalysts during Partial Oxidation and Steam Reforming of Methane

AbstractThe paper shows the structural changes of copper and nickel catalysts in the presence of strong (O2) and weak (H2O) oxidizing agents and their influence on the course of methane conversion. The changes in oxidation states of investigated catalysts were studied during partial oxidation and steam reforming of methane using an X‐ray reactor chamber (XRD) coupled with an online mass spectrometer. Also, the susceptibility of these catalysts to oxidation and reduction by individual reaction components was investigated using TPR, TPO, and in situ XPS techniques. The obtained results indicated the distinct catalytic behavior of copper and nickel catalysts depending on their oxidation state and the importance of coke formation in the activation of the partial oxidation process. The mechanism of re‐reduction of catalysts under reaction conditions and a method to increase the activity of nickel catalysts are proposed.

How local electric field regulates C–C coupling at a single nanocavity in electrocatalytic CO2 reduction

C–C coupling is of utmost importance in the electrocatalytic reduction of CO2, as it governs the selectivity of diverse product formation. Nevertheless, the difficulties to directly observe C–C coupling pathways at a specific nanocavity hinder the advances in catalysts and electrolyzer design for efficient high-value hydrocarbon production. Here we develop a nano-confined Raman technology to elucidate the influence of the local electric field on the evolution of C–C coupling intermediates. Through precise adjustments to the Debye length in nanocavities of a copper catalyst, the overlapping of electrical double layers drives a transition in the C–C coupling pathway at a specific nanocavity from *CHO–*CO coupling to the direct dimerization of *CO species. Experimental evidence and simulations validate that a reduced potential drop across the compact layer promotes a higher yield of CO and promotes the direct dimerization of *CO species. Our findings provide insights for the development of highly selective catalyst materials tailored to promote specific products.

Cu/MgO as an Efficient New Catalyst for the Non-Oxidative Dehydrogenation of Ethanol into Acetaldehyde

The non-oxidative dehydrogenation of ethanol into acetaldehyde is one of the efficient solutions for biomass upgrading. In this work, a series of copper catalysts supported on MgO with different Cu loadings ranging from 2.5% to 20% were prepared by an impregnation method. The as-synthesized Cu/MgO catalysts were characterized by N2 adsorption, XRD, TEM, CO2-TPD, XPS and TPR. These catalysts were found to be effective for ethanol dehydrogenation into acetaldehyde. As the Cu loading was increased, the ethanol conversion first increased and then leveled off. At a WHSV of 1.5 h−1 and 250 °C, the 20%Cu/MgO catalyst gave an initial conversion of 81.5%, with 97.7% selectivity toward acetaldehyde. Compared to 20%Cu/SiO2, the 20%Cu/MgO catalyst displayed an equivalent initial acetaldehyde yield, higher acetaldehyde selectivity and longer stability.

Unsupported Nanoporous Copper Catalyst for the Carboxylation of Terminal Alkynes with Carbon Dioxide

AbstractAn unsupported nanoporous copper catalyst (CuNPore) with highly bicontinuous nanostructure was prepared by a chemical dealloying method. Various characterization methods were used to investigate the structure and composition of CuNPore, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS). Active species of cuprous oxide were found on the surface of CuNPore catalyst. The nanoporous structure and the presence of Cu(I) enable CuNPore to catalyze the carboxylation reaction of terminal alkynes with CO2 under mild conditions. A wide range of terminal alkynes were tolerated to afford the alkynyl carboxylic acids in good to excellent yields. CuNPore catalyst can be easily recovered and recycled five times without any loss of activity.

(Semi)hydrogenation of enoates and alkynes effected by a versatile, particulate copper catalyst

We communicate a versatile and user-friendly Cu-based catalytic method that allows for the selective hydrogenation of enoates and alkynes. The introduced protocol is free from any ex ante modifications of the used Cu(I) precursors by air-sensitive phosphines or elaborate N-heterocyclic carbene ligands. The conjugate hydrogenation of enoates and the (selective) reduction of CC bonds is achieved through a [Cu(CH3CN)4]+/tert-butoxide pair whereby we describe a delicate influence of the base cation on the chemoselectivity of the respective transformation. In case of the ester-to-alcohol reduction, a combination of simple CuI and NaOtBu proved to be successful. Deuteration experiments are included to address certain mechanistic aspects of the introduced catalytic system. All requisite chemicals are readily obtainable through commercial channels and the catalyst assembly is set up on the bench without the need for special lab-technical precautions.

In-situ activation of biomimetic single-site bioorthogonal nanozyme for tumor-specific combination therapy

Copper-catalyzed click chemistry offers creative strategies for activation of therapeutics without disrupting biological processes. Despite tremendous efforts, current copper catalysts face fundamental challenges in achieving high efficiency, atom economy, and tissue-specific selectivity. Herein, we develop a facile “mix-and-match synthetic strategy” to fabricate a biomimetic single-site copper-bipyridine-based cerium metal-organic framework (Cu/Ce-MOF@M) for efficient and tumor cell-specific bioorthogonal catalysis. This elegant methodology achieves isolated single-Cu-site within the MOF architecture, resulting in exceptionally high catalytic performance. Cu/Ce-MOF@M favors a 32.1-fold higher catalytic activity than the widely used MOF-supported copper nanoparticles at single-particle level, as first evidenced by single-molecule fluorescence microscopy. Furthermore, with cancer cell-membrane camouflage, Cu/Ce-MOF@M demonstrates preferential tropism for its parent cells. Simultaneously, the single-site CuII species within Cu/Ce-MOF@M are reduced by upregulated glutathione in cancerous cells to CuI for catalyzing the click reaction, enabling homotypic cancer cell-activated in situ drug synthesis. Additionally, Cu/Ce-MOF@M exhibits oxidase and peroxidase mimicking activities, further enhancing catalytic cancer therapy. This study guides the reasonable design of highly active heterogeneous transition-metal catalysts for targeted bioorthogonal reactions.

Modeling Bicarbonate Kinetics on Silver Catalysts for CO2 Electrolysis

Low-temperature CO2 electrolyzers transform captured CO2 into more useful chemicals, such as syngas (CO and H2) for systems with silver or gold catalysts and ethylene and other C2+ products for systems with copper catalysts. At low overpotentials, bicarbonate ions act as proton donors and have been shown to have enhanced activity1, leading to nonlinear Tafel slopes for the hydrogen evolution reaction (HER). We have developed a 1D planar electrode model for CO2 electrolysis, similar to the model developed by Gupta et al.,2 including a thin ionomer layer on top of a silver catalyst layer surface. The model includes buffer chemistry and ion transport in the boundary layer as well as the ionomer thin-film layer. Tafel parameters are fit for both bicarbonate and water as proton donors for HER using the model results to account for mass transport in the boundary layer. A comparison against a bare silver electrode shows that the Donnan potential across the ionomer/electrolyte interface has a significant effect on the ion concentrations at the catalyst layer surface, leading to enhanced HER from bicarbonate at low overpotentials. These results are then compared against Butler-Volmer parameters that are derived from a full microkinetic model. The Tafel kinetic parameters were then used in a 1D full-cell membrane electrode assembly (MEA) model, and we found good agreement with experimental data, illustrating that the ionomer in contact with the catalyst layer surface impacts the underlying kinetics both in planar electrodes and industrially-relevant MEA systems.References D. M. Koshy et al., J. Am. Chem. Soc., 143, 14712–14725 (2021) https://doi.org/10.1021/jacs.1c06212.N. Gupta, M. Gattrell, and B. MacDougall, J. Appl. Electrochem., 36, 161–172 (2006). This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was partially supported by a Cooperative Research and Development Agreement (CRADA) between Lawrence Livermore National Laboratory, Stanford University, and TotalEnergies American Services, Inc. (affiliate of TotalEnergies SE) under Agreement No. TC02307 and Laboratory Directed Research and Development (LDRD) funding under project 22-SI-006.LLNL-ABS-857478 Figure 1

CO Residence Time Modulates Multi-Carbon Formation Rates in a Copper Based Zero Gap CO2 Electrolyzer

Carbon dioxide (CO2) electrolysis on copper (Cu) catalysts has attracted interest for its direct production of C2+ feedstocks. Using the knowledge that CO2 reduction on copper is primarily a tandem reaction of CO2 to CO and CO to C2+ products, we show that modulating CO concentrations within the liquid catalyst layer allows for C2+ selectivity of > 80 % at 200 mA cm-2 in a membrane electrode assembly over broad conversion conditions. The importance of CO pooling is demonstrated through residence time distribution curves, varying flow fields (serpentine/parallel/interdigitated), and flow rate. While serpentine flow fields require high conversions to limit CO selectivity and maximize C2+ selectivity, the longer CO residence times of parallel flow fields reach similar selectivity over broad flow rates. Critically, we show that parts of the catalyst area are predominantly reducing CO instead of CO2 as supported by CO reduction experiments and transport modelling of the reactor. In addition, higher cation crossover from the anolyte is shown to maximize C2 + selectivity providing further evidence of cation effect on C-C coupling rates.

The Role of Surface Roughening in Improving the Selectivity of Copper for CO2 Electroreduction

Electroreduction of CO2 (eCO2RR) has emerged as a promising alternative for production of renewable fuels and important commodity chemicals such as ethylene and ethanol. Simultaneously, it opens an economically attractive path to mitigate point sources of CO2, a potent greenhouse gas. Despite decades of research efforts, Cu remains the only catalyst capable of producing significant amounts of desirable C2+ products, containing more than one carbon atom. However, further improvement is needed for industrial applications. It is known that roughened copper-based electrocatalysts surfaces exhibit enhanced selectivity towards C2+ products during electroreduction of CO2. This poses a challenge for modeling efforts aiming to find a rationale for the enhanced selectivity. In this work, we use an innovative modeling approach to investigate roughened copper surfaces derived from cuprous oxide on structures of 100x100 nm2 size with atomic resolution and accuracy compared to density functional theory (DFT). We combine semilocal DFT (RPBE) in VASP, effective medium theory (EMT), and linear scaling relationships via the recently proposed alpha parameter scheme to investigate the site-resolved catalytic selectivity of copper sites. Electrode potential-dependence is included via the use of the VASPsol implicit solvation and a grand canonical potential approach. The approach allows us to investigate the effect of varied macroscopic roughness on the intrinsic catalytic activity of copper by comparing surfaces exposed to simulated sputtering and electropolishing, respectively. The study highlights i) the challenge for designing improved copper catalysts for CO2RR with monodisperse active site selectivity, ii) the need for careful experimentation when comparing to theory, and iii) the limitations of macroscopic roughness in controlling atomic scale activity.

(Invited) Electrosynthesis of Carbon Dioxide to Ethylene

Electrochemical production of hydrocarbons provides a pathway for connecting renewable energy generation with chemical production. In this work, we present research on the targeted electrochemical reduction of carbon dioxide to ethylene, which has a global production volume of over 200 metric tonnes per year. The selectivity of carbon dioxide to ethylene is heavily dependent on cell architecture, surface interfaces, and operating conditions. We explore the tradeoffs of using a zero-gap cell design, and demonstrate the production of ethylene with greater than 30% selectivity at 200 mA/cm2 with an uncompensated full cell voltage of 2.7 V. We also present modifications to a copper catalyst cathode, and the effects of conditioning and variable operation on the electrochemical cell performance including selectivity and durability. Leveraging technoeconomic analyses, we will present the projected costs of this pathway for producing ethylene and conclude with a discussion on long-term operation failure modes which greatly impact the future feasibility of this technology. Figure 1

Copper‐Catalyzed Chan‐Lam Reaction and Sequential [2,3]‐Rearrangement to Prepare α‐Benzotriazinium Ketones

A variety of α‐benzotriazinium ketones were prepared in 38%‐89% yields through a copper(II)‐catalyzed Chan‐Lam reaction and [2,3]‐rearrangement in a one pot reaction open to air from N‐hydroxybenzotriazin‐4‐ones and alkenyl boronic acids at room temperature. Experimental results showed that the copper catalyst not only played as cross‐coupling catalyst but also served as Lewis acid catalyst to control the chemoselectivity of [2,3]‐rearrangement. The reaction tolerated various linear and cyclic disubstituted alkenyl boronic acids. Moreover, α‐benzotriazinium ketone could be easily prepared in gram scales. The present method highlights dual roles of copper catalyst and [2,3]‐rearrangement of N,O‐vinyl moiety.

Selective electroreduction of CO2 to C2+ products on cobalt decorated copper catalysts

Cu-catalyzed electrochemical CO2 reduction reaction (CO2RR) to multi-carbon (C2+) products is often plagued by low selectivity because the adsorption energies of different reaction intermediates are in a linear scaling relationship. Development of Cu-based bimetallic catalysts has been considered as an attractive strategy to address this issue; however, conventional bimetallic catalysts often avoid metals with strong CO adsorption energies to prevent surface poisoning. Herein, we demonstrated that limiting the amount of Co in CuCo bimetallic catalysts can enhance C2+ product selectivity. Specifically, we synthesized a series of CuCox catalysts with trace amounts of Co (0.07-1.8 at%) decorated on the surface of Cu nanowires using a simple dip coating method. Our results revealed a volcano-shaped correlation between Co loading and C2+ selectivity, with the CuCo0.4% catalyst exhibiting a 2-fold increase in C2+ selectivity compared to the Cu nanowire sample. In situ Raman and Infrared spectroscopies suggested that an optimal amount of Co could stabilize the Cu oxide/hydroxide species under the CO2RR condition and promote the adsorption of CO, thus enhancing the C2+ selectivity. This work expands the potential for developing Cu-based bimetallic catalysts for CO2RR.

Bio-Inspired histidine-based copper complex: An efficient and robust electrocatalyst for electrochemical hydrogen evolution

The quest for an efficient and sustainable electrocatalyst for hydrogen evolution reaction (HER) using earth-abundant elements is crucial for cost-effective and environmentally friendly hydrogen production. While many catalysts show good activity and stability in strongly basic conditions, fewer materials are effective under neutral conditions, which are more practical for electrolyzer operations. This study introduces a dinuclear copper catalyst, [Cu2(μ-OH) (μ-NO3) (L)2], where L is the Schiff base ligand derived from salicylaldehyde and histidine amino acid (Complex 1), for HER in both aqueous and non-aqueous environments. In non-aqueous conditions, with acetic acid as a proton source, the catalyst exhibits outstanding HER performance, achieving an overpotential of 170 mV. At an acid concentration of 0.086 M, it achieves a catalytic current of ∼17.5 mA cm−2 at an overpotential of 0.52 V. Remarkably, in fully aqueous neutral conditions, Complex 1 reaches a significant current density with an ic/ip ratio of ∼82 at a scan rate of 1.0 V s−1, and an apparent rate constant (kobs) for electrocatalytic HER of ∼13,200 s−1. The catalyst also shows excellent activity in 0.1 M H3PO4, with low overpotentials of ∼150 mV at 2.0 mA cm⁻2 and 270 mV at 10.0 mA cm⁻2. In controlled potential electrolysis (CPE), the catalyst maintains stable catalytic currents of 25 mA cm⁻2 and 75 mA cm⁻2 for 18–28 h at a potential of 0.590 V vs. RHE in neutral and acidic conditions, respectively, without noticeable decrease in catalytic current. Detailed characterizations confirm the molecular integrity of the catalyst and its predominantly homogeneous catalytic mechanism.

Selective electrochemical H2O2 production by a molecular copper catalyst: A crucial relation between reaction rate and mass transport

Selective electrochemical H2O2 production by a molecular copper catalyst: A crucial relation between reaction rate and mass transport

Cu-Electrocatalysis Enables Vicinal Bis(difluoromethylation) of Alkenes: Unraveling Dichotomous Role of Zn(CF2H)2(DMPU)2 as Both Radical and Anion Source.

The difluoromethyl group (CF2H) serves as an essential bioisostere in drug discovery campaigns according to Lipinski's Rule of 5 due to its advantageous combination of lipophilicity and hydrogen bonding ability, thereby improving the ADME properties. However, despite the high prevalence and importance of vicinal hydrogen bond donors in pharmaceutical agents, a general synthetic method for doubly difluoromethylated compounds in the vicinal position is absent. Here we describe a copper-electrocatalyzed strategy that enables the vicinal bis(difluoromethylation) of alkenes. By leveraging electrochemistry to oxidize Zn(CF2H)2(DMPU)2-a conventionally utilized anionic transmetalating source, we paved a way to utilize it as a CF2H radical source to deliver the CF2H group in the terminal position of alkenes. Mechanistic studies revealed that the interception of the resultant secondary radical by a copper catalyst and subsequent reductive elimination is facilitated by invoking the Cu(III) intermediate, enabling the second installation of the CF2H group in the internal position. The utility of this electrocatalytic 1,2-bis(difluoromethylation) strategy has been highlighted through the late-stage bioisosteric replacement of pharmaceutical agents such as sotalol and dipivefrine.

Liquid Metal-Enabled Tunable Synthesis of Nanoporous Polycrystalline Copper for Selective CO2-to-Formate Electrochemical Conversion.

Copper-based catalysts exhibit high activity in electrochemical CO2 conversion to value-added chemicals. However, achieving precise control over catalysts design to generate narrowly distributed products remains challenging. Herein, a gallium (Ga) liquid metal-based approach is employed to synthesize hierarchical nanoporous copper (HNP Cu) catalysts with tailored ligament/pore and crystallite sizes. The nanoporosity and polycrystallinity are generated by dealloying intermetallic CuGa2 formed after immersing pristine Cu foil in liquid Ga in a basic or acidic solution. The liquid metal-based approach allows for the transformation of monocrystalline Cu to the polycrystalline HNP Cu with enhanced CO2 reduction reaction (CO2RR) performance. The dealloyed HNP Cu catalyst with suitable crystallite size (22.8nm) and nanoporous structure (ligament/pore size of 45nm) exhibits a high Faradaic efficiency of 91% toward formate production under an applied potential as low as -0.3 VRHE. The superior CO2RR performance can be ascribed to the enlarged electrochemical catalytic surface area, the generation of preferred Cu facets, and the rich grain boundaries by polycrystallinity. This work demonstrates the potential of liquid metal-based synthesis for improving catalysts performance based on structural design, without increasing compositional complexity.